Businesses and consumers use a wide variety of fixed and mobile wireless terminals, including cell phones, pagers, Personal Communication Services (PCS) systems, and fixed wireless access devices (e.g., vending machine with cell phone capability). Wireless service providers continually try to create new markets for wireless devices and expand existing markets by making wireless devices and services cheaper and more reliable. As part of this effort, wireless service providers are implementing new services, especially digital data services that, for example, enable a user (or subscriber) to browse the Internet and to send and receive e-mail.
Digital services are provided in 1xEV-DV and 1xEV-D0 wireless networks by means of a packet data channel (PDCH) that transmits packet data to mobile station at a high data rate. To ensure backward compatibility with conventional IS-95 and IS-2000 code division multiple access (CDMA) wireless networks, EV-DV networks support legacy handoff operations in which a source base station controls the handoff of a mobile station from the source base station to a target base station. When the source base station determines that the mobile station should be handed off to the target mobile station, the source bas station transmits a control message to the mobile station to initiate the handoff operation.
However, EV-DV networks also improve upon legacy handoff operations by implementing an autonomous handoff operation that is controlled by the mobile station instead. In a 1xEV-DV/DO network, the mobile station is capable of determining when a handoff is necessary. In response to such a determination, the mobile station transmits a Handoff Request message to the target base station to initiate the handoff operation.
Unfortunately, in a conventional autonomous soft handoff operation, the target base station is not able to reject the cell-switching request from the mobile station. This inability creates problems. Since the mobile station is not aware of the resource availability (e.g., radio channels, signal processors) of the target base station, the mobile station may initiate a handoff operation to an already heavily loaded target base station in which few resources are available. This may result in a failure in the handoff operation. Such a failure may be avoided by reserving more resources at the base station for handoff operations. However, reserving additional resources in this way reduces the overall system capacity for handling calls.
Therefore, there is a need in the art for improved systems and methods for performing handoffs between cells in an EV-DV wireless network. In particular, there is a need for a wireless network that improves the handling of autonomous handoff operations initiated by mobile stations.